Audacity is free, open source software for recording and editing sounds.  
With Audacity one can record live audio, convert tapes and records into 
digital recordings, edit Ogg, MP3, and WAV sound files, and much more.
 
Audacity requires wxGTK2.6 and libsndfile, both of which are available on 
SlackBuilds.org.   This script builds with support for libmad, libvorbis, 
id3tag, and libflac (all of which are included in stock Slackware), but 
they can be removed in the "configure" section of the build script if desired.
